HiTechnic NXT Gyro Sensor (NGY1044)

General

This sensor uses the msensor device class.

	Value
type_id	3*
# Modes	1
Connection	Analog/NXT
* Not unique.

Modes

	Mode 0
mode	NXT-ANALOG-0
Description	Rotational speed
num_values	1
value0	Raw sensor voltage
Min	0
Max	4883 (4.882 V)
units	V
dp (decimal places)	3

Values in the tables that look like ```this``` are the names of sysfs attributes or values returned by said attributes.

Scaling

Since this is an NXT Analog sensor and the exact type cannot be autodetected, we have to use a generic sensor interface. This sensor measures rotational speed in degrees/second. Nominally, 0.00V == -540 deg/sec and 4.88V == 400 deg/sec. However, depending on temperature, there is a small offset, so we have to calibrate the sensor to accommodate this.

Sample usage:

#!/bin/bash

# Sample the raw sensor voltage 10 times and get an average value.
# Sensor should be held perfectly still for this.
total=0
for i in {1..10}
do
        total=$(($total + $(cat value0)))
        # if you are using a compiled language, you will want a delay here (~10msec is good)
done
average=$(($total / $i))

# Set scaling that includes offset from average
# 1.953V is proportional to 400 deg/sec
raw_min=$average
raw_max=$(($average + 1953))
scaled_min=0
scaled_max=400

# Now move the sensor around
watch -n 0.1 echo '$((($(cat value0) - '$raw_min')
* ('$scaled_max' - '$scaled_min')
/ ('$raw_max' - '$raw_min') + '$scaled_min'))'